Water heating solutions: Solar water or heat pump?

Choosing the correct renewable energy hot water solution is a difficult decision for many homeowners. In light of all the options and conflicting information available, we have compiled a detailed list of the advantages and disadvantages of solar water heaters and heat pumps, in order for you to make an informed decision.

Advantages: Heat Pump

Easy installation: The installation of a heat pump doesn’t require intricate plumbing work and is fairly easy to install, on both a commercial and residential level.
Minimum space requirements: A heat pump needn’t be installed on a roof and it can be installed outdoors.
You have hot water 24/7: Because a heat pump relies on electricity, it can provide hot water 24/7 (when there is a dependable electricity supply).
Savings: Heat pumps can save up to 50% of energy required to heat water – this translates into a 20 – 30% savings in electricity cost for a household.

Disadvantages: Heat Pump

Hard water (water with high levels of calcium carbonate) needs to be treated with a water-softening plant, resulting in the cost going up. Maintenance of the salt levels is vital to ensure the ‘recharging’of the ion exchange.
Heat pumps are also noisy and generate the most noise after hot water consumption (At night and early morning). The noise level of a heat pump is measured at 50 decibel.
Heat pumps are less efficient than a solar system in high radiation and low ambient temperatures. This makes a solar water heater more ideal for our winters, where we have cold clear skies. A heat pump will lose 50-70% of its efficiency in sub 5 degree temperatures (a heat pump needs heat from the atmosphere to convert cold water to hot water).
Heat pumps require a lot of maintenance, due to constant moving parts that needs to be replaced from time to time. Maintenance on a heat pump also requires the skills of a plumber, electrician or aircon technician.
The life-cycle of a heat pump is 5-10 years and is completely dependent on electricity to generate hot water.

Advantages: Solar water heater

A solar water heater has a 5/10 year factory warranty – depending on the model.
The life-cycle of a solar water heater is 10+ years – our oldest system is 11 years old and still running.
The quality of the water doesn’t influence the system – a sacrificial magnesium protective anode and double ceramic lined tank prevents corrosion. A solar water heater also handles the issue of calcium carbonate better, as it can be easily scooped out during routine maintenance.
The thermostat and element of a solar water heater last longer as it’s only being used 10% of the time.
A roof-mounted solar water heater doesn’t rely on electricity to provide hot water when the sun is shining. All systems have a back up element, which means that your household will always have hot water, regardless the weather.
There is a variety of solar water heating options available for homeowners who don’t want a solar tank on the roof.
The payback period on a solar water heater is low, with a high return on investment.
A solar water heater can save up to 90% on water heating cost of a household. This translates to 40 to 50% saving on your total electricity bill.

Disadvantages: Solar water heater

High capital upfront investment and installation costs (in comparison to a heat pump in areas with good quality water, otherwise the initial capital costs are the same)
A solar water heater works optimally when the sun shines. If it is overcast, the back-up element kicks in to compensate for the lack of solar energy. The back up element will operate approximately 10% of the year.
Routine maintenance similar to an electric geyser is needed on a solar water heater, but only on the valves and not on the system itself.